Expression motifs that confer tissue and development-specific expression in plants

Abstract

The present invention relates to the use of DNA sequence motifs to regulate gene expression in a tissue- or developmental-specific manner in transgenic plants. The invention generally relates to the engineering and use of G-box related sequence motifs, specifically Iwt and PA motifs, which function as cis-elements of promoters, to regulate the expression of heterologous genes in transgenic plants. PA enhances high level expression in roots, low level expression in leaves and little or no expression in seeds. By contrast, Iwt confers preferential expression in seeds, but in a developmentally-regulated manner.

What is claimed is: 
     
       1. A modified plant promoter comprising (A) a tetrameric tandem direct repeat of the Iwt motif, GTACGTGGCG, (SEQ ID NO:2) and (B) a promoter or a segment of a promoter, wherein said segment has its 3'-end at the nucleotide corresponding to the transcription initiation site of the homologous gene regulated by said promoter or at any nucleotide that is one to nine basepairs 5'-upstream of the nucleotide corresponding to the transcription initiation site, and said segment has its 5'-end at a nucleotide at least 50 basepairs 5'-upstream of said initiation site; and (A) is coupled to the 5'-end of (B) or is inserted into (B) at a site at least 50 basepairs 5'-upstream of the 3'-end of (B). 
     
     
       2. The modified plant promoter of claim 1, wherein (B) is the -90 CaMV 35 S promoter. 
     
     
       3. A modified plant promoter comprising (A) a tetrameric tandem direct repeat of the PA motif, GCCACGTGGC, (SEQ ID NO:3) and (B) a promoter or a segment of a promoter, wherein said modified plant promoter causes the transcription of an operably linked coding sequence preferentially in the roots or leaves of a plant containing said modified plant promoter and said operably linked coding sequence, said segment has its 3'-end at the nucleotide corresponding to the transcription initiation site of the homologous gene regulated by said promoter or at any nucleotide that is one to nine basepairs 5'-upstream of the nucleotide corresponding to the transcription initiation site, and said segment has its 5'-end at a nucleotide at least 50 basepairs 5'-upstream of said initiation site; and (A) is coupled to the 5'-end of (B) or is inserted into (B) at a site at least 50 basepairs 5'-upstream of the 3'-end of (B). 
     
     
       4. The modified plant promoter of claim 3, wherein (B) is the -90 CaMV 35 S promoter. 
     
     
       5. A genetically engineered DNA molecule comprising the modified plant promoter of claim 1, 2, 3 or 4 operatively linked to the coding sequence of a gene of interest, wherein said modified plant promoter is linked to the 5'-end of said coding sequence and said modified plant promoter regulates the transcription of said coding sequence. 
     
     
       6. A transformed plant cell containing a genetically engineered DNA molecule of claim 5. 
     
     
       7. A transgenic plant containing a genetically engineered DNA molecule of claim 5. 
     
     
       8. A transgenic plant containing a chimeric DNA molecule comprising the modified plant promoter of claim 1 or 2 operatively linked to the coding sequence of a gene of interest, wherein said modified plant promoter is linked to the 5'-end of said coding sequence and said modified plant promoter causes the transcription of said coding sequence in seeds. 
     
     
       9. A transgenic plant containing a chimeric DNA molecule comprising the modified plant promoter of claim 3 or 4 operatively linked to the coding sequence of a gene of interest, wherein said modified plant promoter is linked to the 5'-end of said coding sequence and said modified plant promoter causes the transcription of said coding sequence to occur in roots. 
     
     
       10. The transgenic plant of claim 8, wherein said modified plant promoter causes the transcription of said coding sequence preferentially in the embryos or endosperms of said seeds. 
     
     
       11. A transgenic plant containing a chimeric DNA molecule comprising the modified plant promoter of claim 3 or 4 operatively linked to the coding sequence of a gene of interest, wherein said modified plant promoter is linked to the 5'-end of said coding sequence and said modified plant promoter causes the transcription of said coding sequence to occur in leaves.